/*
 * Licensed to Crate under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.  Crate licenses this file
 * to you under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.  You may
 * obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.  See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial
 * agreement.
 */

package io.crate.planner.operators;

import io.crate.expression.symbol.Symbol;

import java.util.List;
import java.util.Map;
import java.util.function.BiFunction;
import java.util.function.Function;

/**
 * Used to map one symbol to another
 * The first argument of the function are the new outputs that the symbol will be "based on"
 *
 * See the usages ({@link LogicalPlan#tryOptimize(LogicalPlan, SymbolMapper)}).
 */
interface SymbolMapper extends BiFunction<List<Symbol>, Symbol, Symbol> {

    static SymbolMapper identity() {
        return (newOutputs, x) -> x;
    }

    static SymbolMapper fromMap(Map<Symbol, Symbol> mapping) {
        Function<Symbol, Symbol> mapper = OperatorUtils.getMapper(mapping);
        return (newOutputs, x) -> mapper.apply(x);
    }

    default SymbolMapper andThen(List<Symbol> outputs, SymbolMapper after) {
        return (newOutputs, x) -> after.apply(newOutputs, apply(outputs, x));
    }
}
